As alehouse said, it depends on your area, but as well as that I would suggest that other considerations might be how "serious" a runner you consider yourself to be, your budget, and how important it is to be in an affiliated club.
As a suggestion you might like to look at the parkrun results for a given week and see which clubs are popular in the results - try Heaton Park parkrun for North Manchester or South Manchester parkrun for, well, you get the idea. Also there are other parkruns if you're further out. Better still come along to a parkrun!
So for South Manchester, http://www.parkrun.org.uk/southmanchester/results/latestresults/ . I'm a bit biased as I've found the Chorlton Runners to be a friendly bunch with a good variety of people training for different races at all levels. The club isn't affiliated (although they are looking at getting affiliated), but they welcome anyone who wants to join in and there's no membership fee, so just turn up and run.
I also run with the Sweatshop group from the Arndale, which again is friendly, free and well attended.
Just google for more details of either.